In a conventional pneumatic tire of the “tubeless” type (that is to say of the type without an inner tube), the radially internal face comprises an airtight layer (or more generally a layer that is impermeable to any inflation gas) which enables the pneumatic tire to be inflated and kept under pressure. Its sealing properties enable it to guarantee a relatively low rate of pressure loss, making it possible to keep the tire inflated, in the normal operating state, for a sufficient time, normally several weeks or several months. It also has the role of protecting the carcass reinforcement from the diffusion of air coming from the internal space of the tire.
This role of airtight inner layer or “inner liner” is today fulfilled by compositions based on butyl rubber (isobutylene/isoprene copolymer), long renowned for their excellent sealing properties.
However, one well-known drawback of compositions based on butyl rubber or elastomer is that they have high hysteresis losses, furthermore over a wide temperature range, which drawback degrades the rolling resistance of pneumatic tires.